Safety-valve



(No Model.) I

' H .'G. ASHTON.

SAFETY VALVE.

No. 303,252. Patented Aug. 12, 1884. k

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UNITED STATES HENRY G. ASHTON, OF SOMEBVILLE, MASSACHUSETTS.

SAFETY-VA LV E.

SPECIFICATION forming part of Letters Patent No. 303,252, dated August12, 1884.

Application filed February 14, 1891. (No model.) Patented in EnglandSeptember-2Z2, 1850, No. 3,849

Qio all; whom it may concern:

Be it known that I, HENRY G. AsHToN, of Somerville, in the county ofMiddlesexand State of Massachusetts, have invented certain new anduseful Improvements in Safety- Valves, (for which I have obtained apatent in Great Britain No. 3,849, hearing date Sep teniber 22-, 1880,)of which the following is a full, clear, concise, and exactdescription,reference being had to the accompanying drawings, making a part hereof,in which Figure l is a vertical section. Fig. 2 is a section on line :0d3 of Fig. 1. Figs. 3 and 1 are details.

My invention relates, primarily, to that class of valves commonly calledpop-valves; and its main feature is an adjustable cock connected withthe pop-chamber, the upward pressure upon the valve, when open, beingregulated by the adjustment of this cock. In all pop-valves the escapingsteam passes first into the pop-chamber, and pressure of the.

steam in this chamber aids in lifting the valve against the force of thespring, and as the area of the opening through which the steam entersthe pop-chamber is determined by the diameter of the valve-seat andthe'height to which the valve rises, the pressurefin the popchainberdepends upon the boiler-pressure and the area of the opening throughwhich the steam escapes from the pop-chamber, as will be clear to allskilled in this art. Moreover, as the pressure required in thepopchamber depends upon the increased tension of the spring caused bythe rising of the valve and the area of the surface exposed to thepressure of the steam in the pop-chamber, the proper area of the outletfrom the pop-chanr ber depends upon the stiffness of the spring, theboiler-pressure, the size of the valve, and the area of the surfaceexposed to the pressure of the steam in the pop-chamber, and very greatnicety and skill are therefore required to make these valves so thatthey will work to good advantage at the desired pressure; and after theyare adjusted for that pressure it is difiicnlt and often impossible toreadjust them for a different pressure, especially when the secondpressure is as much as one-third -more or less than the first.

The first part of my invention is intended to remedy this evil, and itsmain purpose is to furnish a pop-valve which can be made in quantity andthen adjusted for its work. This part of myinvcu-tion is illustrated inthe drawings as applied to that form of pop-valve described in my PatentNo. 200,119, dated February 12, 1878, but is applicable to other formsof pop-valve.

In the drawings, a a represent the popchamber, I) the inlet-opening ofthe pop-chainber, and d the outlet-opening from the popchannber-that isto say, the steam escapes over the corner I) of the bushing or seat 13as soon as the boiler-pressure is suiiicient to start the valve A fromseat 13, and this escaping steam enters the pop-chamber a a and ex pandsin that chamber, its pressure in that chamber (supposing the cock D tobe closed) depending upon the area of the opening at b H and theboiler-pressure on the one hand, and the area of the opening atd on theother hand. Vlhen the lip of the valve at d is formed to rest upon theupper surface of the seat B, a number of small holes, (1, are formedthrough 7 the valve lip, as shown in the. drawings, the opening at (Ibeing insuiiicient, and the total area of the outlet-opening from thepop-chamher being the area of the opening at (I added to the areas ofthe holes d. 8c

It will be seen that I provide an additional opening, (2", from thepop-chamber, and con trol that opening bythe cock D 5 and it is thisadditional opening which is the distinguishing characteristic of myinvention, as by it I can construct the valve with the outlet-openingfrom the pop-chamber much smaller than is requisite in practice-forexample, by re ducing the number of the holes (1, or omitting themaltogether-and with the opening so 0 1 large that the sum of the areasof the usual outlet-openings, (l and 0, (when those holes are used,) andthe additional outlet-opening,

If, will be abundantly large; then by adjusting the area of theadditional outlet-opening, d", 5 the valve can be adjusted readily andwith the utmost accuracy, after the valve is applied to the boiler andwhile exposed to steam-pressure. NVhen the pop-chamber ais as small asin the valve shown, it is well to enlarge it, as shown at a, for greaterease in attaching the cock D to the additional outlet-opening, d

The best form of cock D is a hollow screw, let in, as shown, so that thehollow part of it is open to the pop-chamber. The hole (1 can be broughtto coincide with outlet (7 when the additional outlet, d", is requiredto be wide open, or can be varied with relation to (Z as desired. Thecheek-nut (7* holds screw I) where set. The outlet (7 may lead into theopen air, instead of into the case F, as shown.

Heretofore the safety-valves of steamboats have discharged into the openair with so great a noise as to be in the highest degree objectionablefor many reasons. I' have arranged a safety-valve of a large steamer bycarrying its disehargepipe down below the water-line, and havediscovered that that mode of; discharging the steam doesaway with allobjectionable noise, the very great advantages of which will be plain toall familiar with the navigation and management of steamboats. Any valvewhich is what isknown as an under-discharge pop-valve, (see my PatentNo. 197,072, dated November 13, 1877,) will answer for this purpose; butthe valve shown in the drawings is better adapted for this especial usethan any other known to me, for it is not only an under-dischargepop-valve, but is also a double-seated under-discharge valve, and thefirst of this kind, so far as I know or have any reason to believethatis to say, it is an annular valve, or has two faces or bearings, Z) andf, which, when the valve leaves its seat, afford two outlets for thesteam, and is provided with a head, A, which fits in a cylindrical partof the ease F, so that the pressure of the steam within the ease F isprevented .from aiding to force the valve back on its seat.

within the cylindrical part F by expansion of the air or the leaking ofsteam. between head A and cylinder F. I The cover II is too well knownto need description here.

In a .steamboatvalve a spindle, J, and lever J are desirable; and aminor feature of my invention consists in a novel combination of valve,its spindle, its spring, and the screw and nut by which the spring isadjusted. The spindleJ is pivoted on the valve and is formed with aconvex collar, j, at its lower end. By this collar the disk j issupported, and the lower end of the valve-spring j" rests upon this diskj. The upper end of the valvespring j is pressed upon by the disk j,which is pressed upon by the convex collar j on nut and nut is actuatedby hollow screw j, through which spindle J passes. Nut j cannot turn incase F, but screw j can be turned after loosening check-nut j toincrease or decrease the tension of spring j \Vhat I claim as myinvention is- 1. In a pop safety-valve, the additional outlet, (P, fromthe pop-chamber a a, controlled by cock D, substantially as described.

2. In combination, annular valve A, having two faces or bearings, 72 andf, head A, exterior case, F, and interior case, F, the case F serving toconfine the waste steam and compel it to pass through a pipe leadingfrom case F, and the interior case, F, in connection with head A,serving to form an interior chamber open to the atmosphere, all socombined to- 75 gether, substantially as shown. that the pressure of thewaste steam shall be upon the interior of case F and upon the exteriorof case F and head A, the pressure within the chamber formed by case Fand head A remaining substantially atmospheric. f

3. In a safety -valve, the combination of spindle J, pivoted upon thevalve, and having collar j, with disk j, spring disk j, collar j, nut jand screw j, substantially as described.

HENRY G. ASHTON.

WVitnesses:

W. A. COPELAND, WM. ZITTEL.

